Time will tell.
On a purely practical note, even if the Sussexes were in the wrong behind the scenes and exhibiting less than stellar behavior — I still empathize with the idea of not wanting to be in Sandringham. Just seems sort of dreary... And everyone, including the most attention-seeking stars need breaks from photographers and things after awhile. Who wants to be judged on the state of their weight and how they look on Christmas?! And one’s first Christmas as a new mom at that?